Time-dependent ghost Gutzwiller nonequilibrium dynamics

We introduce the time-dependent ghost Gutzwiller approximation (TD-gGA), a nonequilibrium extension of the ghost Gutzwiller approximation (gGA), a powerful variational approach which systematically improves on the standard Gutzwiller method by including auxiliary degrees of freedom. We demonstrate the effectiveness of TD-gGA by studying the quench dynamics of the single-band Hubbard model as a function of the number of auxiliary parameters. Our results show that TD-gGA captures the relaxation of local observables, in contrast with the time-dependent Gutzwiller method. This systematic and qualitative improvement leads to an accuracy comparable with time-dependent dynamical mean-field theory which comes at a much lower computational cost. These findings suggest that TD-gGA has the potential to enable extensive and accurate theoretical investigations of multiorbital correlated electron systems in nonequilibrium situations, with potential applications in the field of quantum control, Mott solar cells, and other areas where an accurate account of the nonequilibrium properties of strongly interacting quantum systems is required.